feat: v3 robustness upgrade — EasyOCR, failure recovery, minimum content check

- OCR: EasyOCR (primary, ch_sim+en) with PaddleOCR fallback for Windows compatibility
- Validation: _check_minimum_content() rejects empty-shell JRXML (no band/textField)
- Retry: MAX_RETRY 3→5, exhaustion records pending_failure_context for next-turn auto-injection
- Finalize: only saves jrxml_versions on pass, preserves last good final_jrxml on fail
- Extract JRXML: improved empty markdown block handling and XML fragment fallback
- UI: real-time node progress via placeholder updates, initial "analyzing" feedback
- UI: use agent_state (full) instead of node_state (partial) for summary card routing
- UI: unknown template_type now gives LLM meaningful image context instead of metadata
- Docs: updated CLAUDE.md and CODE_GUIDE.md to reflect all v3 changes

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

validation_service/main.py

@@ -82,6 +82,35 @@ def _check_structural_issues(jrxml: str) -> list[str]:
     return issues
 
 
+def _check_minimum_content(jrxml: str) -> list[str]:
+    """检查 JRXML 是否包含最基本的报表内容（至少要有 band 和文本元素）。"""
+    issues = []
+    try:
+        root = ET.fromstring(jrxml)
+    except ET.ParseError:
+        return []  # 结构性检查已捕获
+
+    # 统计各类元素
+    bands = 0
+    text_fields = 0
+    static_texts = 0
+    for elem in root.iter():
+        tag = elem.tag.split("}")[-1] if "}" in elem.tag else elem.tag
+        if tag == "band":
+            bands += 1
+        elif tag == "textField":
+            text_fields += 1
+        elif tag == "staticText":
+            static_texts += 1
+
+    if bands == 0:
+        issues.append("报表没有任何 <band> 元素，无法渲染内容")
+    if text_fields == 0 and static_texts == 0:
+        issues.append("报表没有任何 <textField> 或 <staticText> 元素，输出将是一片空白")
+
+    return issues
+
+
 def _validate_xsd(jrxml: str) -> tuple[bool, str]:
     """根据 JasperReports XSD schema 验证 JRXML。"""
     if not SCHEMA_FILE.exists():
@@ -111,6 +140,10 @@ async def validate_jrxml(req: ValidationRequest):
     if structural_issues:
         return ValidationResponse(valid=False, error="; ".join(structural_issues))
 
+    content_issues = _check_minimum_content(jrxml)
+    if content_issues:
+        return ValidationResponse(valid=False, error="; ".join(content_issues))
+
     valid, xsd_error = _validate_xsd(jrxml)
     if not valid:
         return ValidationResponse(valid=False, error=xsd_error)